1. Field of the Invention
The invention relates to a device for preparing froth, in particular for preparing milk froth by means of hot steam output by a domestic coffee machine.
2. Discussion of Prior Art
DE 35 38 041 C2 discloses a device for heating and emulsifying milk, which can be used in particular for preparing cappuccino. This device has an elongate nozzle body having a rear end and a front end, which is connected in the region of its rear end to a hot steam source, as fitted in some domestic coffee machines. An outlet nozzle is situated in the region of the front end of the nozzle body. The nozzle body is surrounded by a casing sleeve which has an air intake opening in the region of its rear end and an outlet opening in the region of its front end, an intermediate space being provided between the nozzle body and the casing sleeve. Furthermore, the casing sleeve has a liquid intake opening in the region of its front end.
In order to produce the milk froth for a cappuccino drink using the previously known device, the device is submerged with its front end region into a vessel containing milk while hot steam is conducted into the nozzle body from an external source. When the hot steam flows out at the front end of the nozzle body, it entrains, via a venturi effect, air flowing through the air intake opening and the intermediate space between casing sleeve and nozzle body, so that a mixture of hot steam and air enters the milk, which causes the milk to emulsify and break up. Furthermore, a venturi effect likewise causes milk to be conveyed through the front region of the device through the liquid intake opening submerged in the milk, which leads to a further swirling and improvement of the froth formation.
A similar device is known from DE 88 06 220 U1, but a liquid intake opening is not provided therein.